1、Designation: B 939 05Standard Test Method forRadial Crushing Strength, K, of Powder Metallurgy (P/M)Bearings and Structural Materials1This standard is issued under the fixed designation B 939; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the equipment and laboratoryprocedure for the determination of the radi
3、al crushing strengthof materials using either a plain powder metallurgy (P/M)bearing or a hollow cylindrical test specimen. This is adestructive test that produces quantitative results.1.2 Limitations:1.2.1 The principle of this procedure is based on thematerial being tested having minimal ductility
4、. The permanentdeflection of the cylinder during the test should not exceed10 % of the outside diameter.1.2.2 The radial crushing strength test results should be usedonly as a guide if the test specimen has a wall thickness that isgreater than one-third of the outside diameter. These test resultssho
5、uld then only be used for comparison with data from the testspecimens of like materials and similar dimensions.1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand ar
6、e not considered standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations pr
7、ior to use.2. Referenced Documents2.1 ASTM Standards:2B 243 Terminology of Powder MetallurgyB 438/B 438M Specification for Sintered Bronze Bearings(Oil-Impregnated)B 439 Specification for Iron Base Sintered Bearings (Oil-Impregnated)B 612 Specification for Iron Bronze Sintered Bearings (Oil-Impregna
8、ted)B 782 Specification for Iron Graphite Sintered Bearings(Oil-Impregnated)B 925 Practices for Production and Preparation of PowderMetallurgy (P/M) Test Specimens2.2 MPIF Standard:3MPIF Standard 55 Determination of Radial Crush Strength(K) of Powder Metallurgy Test Specimens3. Terminology3.1 Defini
9、tionsDefinitions of powder metallurgy (P/M)terms can be found in Terminology B 243. Additional descrip-tive information is available in the related material section ofVol 02.05 of the Annual Book of ASTM Standards.4. Summary of Test Method4.1 Radial crushing strength is determined by subjecting apla
10、in sleeve bearing or a thin-walled cylindrical test specimento a controlled compressive force applied perpendicular to itscentral axis under uniformly increasing load until fractureoccurs.4.2 The term radial crushing strength as used in this testmethod is the stress at fracture calculated from the b
11、reakingload and the dimensions of the test specimen.5. Significance and Use5.1 The radial crushing strength test is a destructive proce-dure used to determine a material strength characteristic of P/Mbearings and hollow cylindrical test specimens. These data canbe used to grade, classify, and evalua
12、te the materials.5.2 The P/M bearing Specifications B 438/B 438M, B 439,B 612, and B 782 require the use of this test method as anacceptance test for the strength of oil-impregnated sinteredbearings.5.3 This test method may be used by powder producers andparts manufacturers as a lot acceptance test
13、for metal powdersand premixes intended for the production of porous parts.1This test method is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Products and is the direct responsibility of Subcom-mittee B09.04 on Bearings.Current edition approved Oct. 1, 2005. Published
14、November 2005.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Metal Powder Industries Federat
15、ion (MPIF), 105 College Rd.East, Princeton, NJ, 08540-6692, USA1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.4 Companies in the P/M industry use this test as amanufacturing control test because it is appropriate for pro-duction p
16、ractices.5.5 Radial crushing strength is a property of the P/Mmaterial but is not a design value. However, experience hasshown that the radial crushing strength of a material isapproximately twice its ultimate tensile strength.6. Apparatus6.1 Measuring EquipmentMicrometers, calipers, and pluggages c
17、apable of measuring the inside and outside diametersand length of the test specimen to the nearest 0.001 in. (0.03mm).6.2 Compression Testing MachineA compression ma-chine capable of applying a controlled breaking force to the testspecimen with an accuracy of 1 % and readable to the nearest10 lbf (5
18、0 N).6.3 Loading PlatesTwo flat, ground-hardened steel platesof sufficient size to encompass the test specimen that can befastened to the press platens and that will remain parallelwithin 0.002 in./in. (mm/mm) under load.7. Test Specimens7.1 The test specimen shall be a right circular thin-walledhol
19、low cylinder.7.1.1 When metal powders are to be evaluated, the testspecimen shall be produced according to the procedure inPractices B 925.7.1.2 If bearings are to be evaluated, the test specimen maybe a plain sleeve bearing taken from a production lot or otherbearing machined to a plain cylindrical
20、 shape.8. Procedure8.1 Clean any surface oil from the specimen and measurethe outside diameter, inside diameter, and the length to thenearest 0.001 in. (0.03 mm).8.2 Wipe the loading plates clean and lay the test specimenin the central region of the lower plate.8.3 Bring the upper plate and test spe
21、cimen into contact andslowly apply the diametrical load at a rate that does not exceed0.2 in./min (5 mm/min) (see Fig. 1).8.4 Using a scale on the compression testing machine thathas a precision of 1 % or better of the crushing load, record tothe nearest 10 lbf (50 N) the load at which the test spec
22、imenfractures or the first reading at which the applied load drops.9. Calculation9.1 Use Eq 1 to calculate the radial crushing strength of thematerial in the specimen.K 5PSD 1 d2DLSD 2 d2D25PD 2 t!Lt2(1)where:K = radial crushing strength, psi (MPa),P = breaking load, lbf (N),D = outside diameter, in
23、. (mm),d = inside diameter, in. (mm),L = length, in. (mm), andt = wall thickness (D d)/2, in. (mm).10. Report10.1 The radial crushing strength, calculated as the averageof three determinations, shall be reported to the nearest 1000psi (10 MPa).10.2 The following information may also be included in t
24、hereport:10.2.1 Origin and processing of the test specimen,10.2.2 Chemical composition of the material,10.2.3 Density of the bearing or test specimen beforetesting, and10.2.4 Details of any deviation from the test method and anyconditions or occurrences that may have affected the testresults.11. Pre
25、cision and Bias11.1 PrecisionThe precision of this test method (Table 1)was determined by the Standards Committee of the MetalPowder Industries Federation for MPIF Standard 55.411.2 BiasInformation cannot be presented on the bias ofthis test method for measuring radial crushing strength becauseno ma
26、terial having an accepted reference value is available.12. Keywords12.1 K; material strength; P/M bearings; radial crushingstrength4The precision is used herein with the permission of the Metal Powder IndustriesFederation (MPIF), 105 College Rd. East, Princeton, NJ, 08540-6692, USA.TABLE 1 Precision
27、 DataMaterialMed GraphiteBronzeCTG-1001-K23Iron-CopperFC-1000-K20Copper-SteelFC-0208-50Dry Density (g/cm3) 6.56 5.96 6.76Outside Diameter, D in. (mm) 1.00 (25.4) 1.00 (25.4) 2.00 (50.8)Inside Diameter, d in. (mm) 0.75 (19.1) 0.75 (19.1) 0.875 (22.2)Length, L in. (mm) 0.75 (19.1) 0.75 (19.1) 0.75 (19
28、.1)Number of Labs 9 9 10Radial CrushingStrength, K psi (MPa) 31 000 (215) 58 000 (400) 114 000 (785)Repeatability, r psi (MPa) 2200 (15) 4900 (35) 6900 (50)Reproducibility, R psi (MPa) 3300 (25) 6600 (45) 6900 (50)B939052ASTM International takes no position respecting the validity of any patent righ
29、ts asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any
30、time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments wil
31、l receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by AST
32、M International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).FIG. 1 Diametrical Load Applied to the Upper Plate and Test SpecimenB939053
